The stock was downgraded Monday by Goldman Sachs and this morning by Banc of America Securities.
No reason for Kent's departure was given, but his employment contract was set to expire December 23. Kent, who has been credited with much of the company's growth, said he would continue as a consultant.
After making generally positive comments on the cable sector and Charter in particular, Goldman downgraded the stock to market outperform from its recommended list. Banc of America cut to buy from strong buy.